1. Field of the Invention
The present invention relates to a liquid crystal television and a liquid crystal display apparatus which comprise a stand, and a main body having a liquid crystal display surface on which images are presented, and being supported by the stand to be rotatable relatively to the stand around a rotation axis extending toward the stand.
2. Description of the Prior Art
There is known a liquid crystal television comprising a stand, and a main body having a resin cabinet and a liquid crystal display surface on which images are presented, and being supported by the stand to be rotatable relatively to the stand around a vertical rotation axis. The stand comprises a metallic bottom plate member having a plurality of countersunk holes and disposed at the bottom of the stand, an upper cover of resin having a plurality of first screw holes of a first and a second group formed in a lower surface thereof at positions respectively corresponding to the countersunk holes of a first and a second group so that the bottom plate member and the upper cover are secured together by first screws, a guide member of resin having a plurality of screw holes which are formed through the thickness of the guide member at respective positions corresponding to the countersunk holes of the first group so that the guide member is also screwed together with the bottom plate member and the upper cover, and a metallic support unit which is supported by the guide member such that the support unit is rotatable relatively to and along the guide member, and supports the main body of the television.
The upper cover is secured to the bottom plate member by inserting second screws through the countersunk holes of the second group and the first screw holes of the second group as aligned with the countersunk holes of the second group, and tightening the second screws. The guide member is annular, and its second screw holes are aligned with the countersunk holes of the first group and the first screw holes of the first group so that the guide member is fixed between the bottom plate member and the upper cover by the first screws and in a horizontal position with the center of the guide member on the vertical rotation axis.
In the conventional television constructed as described above, the main body supported by the support unit is capable of swiveling around the rotation axis extending vertically.
To form in the bottom plate member the countersunk holes, namely, the holes with their one end outwardly tapered, through-holes for inserting the screws are first punched out in a metal sheet and then countersinks are formed by pressing, causing plastic deformation at a periphery of an open end of each of the through-holes which is open in a surface of the metal sheet to be a lower surface of the bottom plate member.
Japanese Patent Application Laid Open No. 63-36932 discloses a technique in which a hole is initially punched in a metal sheet to be a metal plate member in a first pressing step, and then a countersink is formed at an open end of the prepared hole in a second pressing step. In the technique of this publication, slits are formed in the metal sheet to be radially arranged around the prepared hole, so that, in the second pressing step for forming the countersink, the material forming the metal plate member is plastically deformed to flow into the slits contiguous with the prepared hole.
In the former technique, as shown in FIG. 18, when a countersink 5 is formed by pressing using a punch 3 and a die 4, after a through-hole 2 is punched in a metal sheet 1, using a punch and a die for instance, a rise of the material may occur around the through-hole 2. Such a material rise causes a deformation of the guide member when the guide member and the bottom plate member are screwed together, generating a relatively large friction force between the support unit and the guide member when the main body of the television is swiveled, since the main body is supported by the support unit which is rotated along the guide member. Accordingly, this conventional technique suffers from unsmooth swiveling of the main body.
When the latter technique where the slits contiguous with the prepared hole are provided is employed in manufacturing of the liquid crystal display apparatus or liquid crystal television, the shape of a plurality of the prepared holes inevitably varies, causing a variation or error in screwing positions when the guide member and the bottom plate member are screwed together. This results in a deformation of the guide member which hinders smooth swiveling of the main body of the television.
Japanese patent Application Laid Open No. 6-5905 discloses a technique of closing a prepared hole by pressing, but does not teach a solution of the problem of the unsmooth swiveling of the main body.